Electronic device and method of transmitting content item

ABSTRACT

According to one embodiment, an electronic device includes a content transmitter. The content transmitter is configured to output a content item including first data and second data to one transmission path, by applying a first copyright protection system to copyright protection of the first data and applying a second copyright protection system to copyright protection of the second data. The first copyright protection system involves encryption of data to be copyright-protected. The second copyright protection system involves no encryption of data to be copyright-protected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2011-189374, filed Aug. 31, 2011,the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a content transmissiontechnique configured to transmit a content item a copyright of whichrequires protection through a transmission path such as a local areanetwork (LAN) or the like.

BACKGROUND

In recent years, electronic devices capable of handling a digitalizedvideo or audio such as personal computers and smartphones have becomewidespread. An electronic device of this type generally incorporatestherein a data communication function, and is capable oftransmitting/receiving audio-visual (AV) content between itself andother electronic devices.

On the other hand, among the AV content items, there are quite a numberof content items the copyright of which requires protection by, forexample, limiting duplication. Accordingly, various contrivancesconfigured to transmit/receive AV content items between a plurality ofelectronic devices while effecting copyright protection have hithertobeen proposed.

As a system configured to protect a visual copyright, for example, thehigh-bandwidth digital content protection system (HDCP) is known.Further, as a system configured to protect an audio copyright, forexample, the serial copy management system (SCMS) is known. The HDCP isa system involving encryption of data to be copyright-protected, and theSCMS is a system involving no encryption of data to becopyright-protected. Accordingly, regarding the video and audio includedin one AV content item, although the object of copyright protection iscommon to both of them, a case where they differ from each other indegree of countermeasure to be required as copyright protection, such asa case where encryption is required of one of them, whereas so far asencryption is not required of the other one is conceivable.

Incidentally, heretofore, only one copyright protection system has beenadopted to transmit one AV content item to one transmission path, andadopting a plurality of copyright protection systems to transmit one AVcontent item to one transmission path has not totally been conceived.Accordingly, for example, it has been necessary to subject even theaudio of which so far as encryption is not required to encryption to berequired of only the video. In such a case, however, in the electronicdevice on each of both the transmission side and reception side of theAV content, a useless increase in cost resulting from incorporatingtherein a module (which is originally unnecessary) configured toencrypt/decrypt the audio is brought about.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theembodiments will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrate theembodiments and not to limit the scope of the invention.

FIG. 1 is an exemplary view showing a system configuration of acopyright-protected content transmission system according to a firstembodiment.

FIG. 2 is an exemplary flowchart showing operation procedures on thecontent transmitter side of the copyright-protected content transmissionsystem of the first embodiment.

FIG. 3 is an exemplary flowchart showing procedures of video encodingprocessing to be executed by the content transmitter of thecopyright-protected content transmission system of the first embodiment.

FIG. 4 is an exemplary flowchart showing procedures of audio encodingprocessing to be executed by the content transmitter of thecopyright-protected content transmission system of the first embodiment.

FIG. 5 is an exemplary flowchart showing procedures on the contentreceiver side of the copyright-protected content transmission system ofthe first embodiment.

FIG. 6 is an exemplary flowchart showing procedures of video decodingprocessing to be executed by the content receiver of thecopyright-protected content transmission system of the first embodiment.

FIG. 7 is an exemplary flowchart showing procedures of audio decodingprocessing to be executed by the content receiver of thecopyright-protected content transmission system of the first embodiment.

FIG. 8 is an exemplary view showing functional blocks of a transmissionfunction of a content item provided with copyright protection, thetransmission function being incorporated in the content transmitter ofthe copyright-protected content transmission system of the firstembodiment.

FIG. 9 is an exemplary view showing a system configuration of acopyright-protected content transmission system according to a secondembodiment.

FIG. 10 is an exemplary view showing functional blocks of a transmissionfunction of a content item provided with copyright protection, thetransmission function being incorporated in a content transmitter of thecopyright-protected content transmission system of the secondembodiment.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

In general, according to one embodiment, an electronic device includes acontent transmitter. The content transmitter is configured to output acontent item including first data and second data to one transmissionpath, by applying a first copyright protection system to copyrightprotection of the first data and applying a second copyright protectionsystem to copyright protection of the second data. The first copyrightprotection system involves encryption of data to be copyright-protected.The second copyright protection system involves no encryption of data tobe copyright-protected.

First Embodiment

First, a first embodiment will be described below.

FIG. 1 is an exemplary view showing a system configuration of acopyright-protected content transmission system according to thisembodiment.

As shown in FIG. 1, the copyright-protected content transmission systemof this embodiment is constituted of a content transmitter 1, contentreceiver 2, and audio reproducer 3. It is assumed that the contenttransmitter 1 and the content receiver 2 are connected to each other by,for example, a wireless LAN (Wi-Fi) of IEEE 802.11, and the contentreceiver 2 and the audio reproducer 3 are connected to each other by,for example, S/PDIF.

The content transmitter 1 is, for example, a personal computer (PC),encodes the content item (video to be output to a display or the like,and audio to be output to a speaker or the like), and thereaftertransmits the encoded content item to the content receiver 2 by Wi-Fi.

The content receiver 2 is, for example, a TV receiver, decodes the(encoded) content item received from the content transmitter 1, anddisplays the video on a screen. Regarding the audio, it is output, afterthis decoding, from a speaker incorporated in the content receiver 2 orthe audio reproducer 3 via S/PDIF.

The data format of the content item to be transmitted between thecontent transmitter 1 and content receiver 2 is, for example, theMPEG2-TS format, and the transmission protocol is, for example, thereal-time transport protocol (RTP). Further, the copyright-protectedcontent transmission system of this embodiment applies, for example, thehigh-bandwidth digital content protection system (HDCP) 2.0 or asucceeding standard of the HDCP 2.0 as the copyright protection system(first copyright protection system) configured to protect the video ES,and applies, for example, the serial copy management system (SCMS) asthe copyright protection system (second copyright protection system)configured to protect the audio ES. That is, in transmitting one contentitem through one transmission path, the copyright-protected contenttransmission system of this embodiment applies a plurality of copyrightprotection systems to the one content item.

First, with reference to FIG. 2, operations on the content transmitter 1side among procedures in the copyright-protected content transmissionsystem of this embodiment from transmission of the video and audio to becarried out by the content transmitter 1 to reproduction of the videoand audio to be carried out by the content receiver 2 will be describedbelow.

After the power supply of the content transmitter 1 is turned on, when acontent transmission application (program) is activated by a useroperation, the content transmitter 1 attempts to achieve connection tothe content receiver 2 via Wi-Fi. When the connection to the contentreceiver 2 is established (block A1), the content transmitter 1 executesprocessing of authentication and key exchange conforming to the HDCP 2.0between itself and the content receiver 2 (block A2). Thereby, theencryption key for the video ES to be used when the content itemprovided with copyright protection (content item the copyright of whichrequires protection) is transmitted, and part (r_(iv)) of the initialvector (IV) are determined.

The content transmitter 1 starts encoding of the video to be output to adisplay or the like, and audio to be output to a speaker or the like(block A3). Regarding details of the encoding processing of the video,and encoding processing of the audio, a description will be given laterby using FIG. 4 and FIG. 5. For example, when a content item providedwith copyright protection, and written to a DVD is being reproduced byusing, for example, a DVD player application or the like (YES in blockA4), the content transmitter 1 sets a copy protection (CP) flag asdetermination of whether or not to require copyright protection (blockA5). It should be noted that here the specification stating that thecontent item to be transmitted should be reproduced by the contenttransmitter 1, and the reproduced content item should be re-encoded andtransmitted to the content receiver 2 is made the premise, and hencealthough it is determined whether the CP flag is set or clear on thebasis of presence/absence of reproduction of the DVD for the sake ofsimplification, copyright protection information embedded in the DVDitself may also be added to the determination criterion.

Immediately after the activation of the content transmissionapplication, either when the CP flag is cleared or set (YES in blockA6), the content transmitter 1 generates a program map table (PMT)describing a PID of each of the video ES and audio ES (block A7) and,further when the CP flag is set (YES in block A8), the contenttransmitter 1 inserts a registration_descriptor specified by the HDCP2.0 in the PMT (block A9). The content transmitter 1 inserts an MPEG2-TSpacket including the generated PMT in the content data to be transmittedto the content receiver 2. The PMT may also be generated at intervals ofa predetermined period such as one second or the like in order toconfirm stream information on the content receiver 2 side, and may beinserted in the content data. The PMTs generated by the above operationare of the same data as long as the CP flag is not toggled.

Subsequently, the content transmitter 1 generates content data of theMPEG2-TS format by the multiplexing (MUX) processing by using contentdata of the PES format generated by video encoding and audio encoding tobe described later (block A10), and transmits the generated content datato the content receiver 2 according to the RTP (block A11). While thecontent transmission application is operated, the content transmitter 1repeats the above-mentioned operations in sequence.

FIG. 3 is an exemplary flowchart showing procedures of video encodingprocessing.

The content transmitter 1 first encodes, in the PES format, the videooutput to the display or the like in accordance with a codec such as theH.264 or the like (block B1).

When the CP flag is set (YES in block B2), the content transmitter 1determines inputCtr,streamCtr specified by the HDCP 2.0 which is part ofthe initial vector, and generates PES_private_data specified also by theHDCP 2.0 (block B3). Next, the content transmitter 1 combines thedetermined inputCtr,streamCtr, and the encryption key and part (r_(iv))of the initial vector generated by the key exchange processing (blockA2) with each other to set the encryption key and initial vector (blockB4). The content transmitter 1 encrypts the PES payload according to theAES-CTR system employed in the HDCP 2.0 (block B5), and inserts thegenerated PES_private_data in the PES header (block B6). Further, thecontent transmitter 1 outputs the generated video PES to the MUX (blockB7). While the content transmission application is operated, the contenttransmitter 1 repeats the above-mentioned operations in sequence.

FIG. 4 is an exemplary flowchart showing procedures of audio encodingprocessing.

The content transmitter 1 first encodes, in the PES format, the audiooutput to the speaker or the like in accordance with a codec such as theAAC or the like (block C1). The content transmitter 1 outputs thegenerated audio PES to the MUX (block C2). While the contenttransmission application is operated, the content transmitter 1 repeatsthe above-mentioned operations in sequence.

It should be noted that when Wi-Fi connection is carried out inaccordance with the WPA system or the like, the part on the transmissionpath is encrypted although it is not encrypted as the audio PES, and thecontent data is transmitted. That is, in this case, the whole contentdata of the MPEG2-TS format including the audio ES is encrypted.

Next, with reference to FIG. 5, operations on the content receiver 2side among procedures in the copyright-protected content transmissionsystem of this embodiment from transmission of the video and audio to becarried out by the content transmitter 1 to reproduction of the videoand audio to be carried out by the content receiver 2 will be describedbelow.

After the power supply of the content receiver 2 is turned on, whenswitching of the mode to the content transmission mode is carried out bya user operation, the content receiver 2 waits for connection theretofrom the content transmitter 1 via Wi-Fi to be carried out. When aconnection request from the content transmitter 1 is received, and theconnection to the content transmitter 1 is established (block D1), thecontent receiver 2 executes the processing of authentication and keyexchange conforming to the HDCP 2.0 between itself and the contenttransmitter 1 (block D2). Thereby, the encryption key for the video ESto be used when the content item provided with copyright protection istransmitted, and part (r_(iv)) of the initial vector are determined.

The content receiver 2 starts decoding of the video and audio (blockD3). Regarding details of the decoding processing of the video, anddecoding processing of the audio, a description will be given later byusing FIG. 6 and FIG. 7.

The content receiver 2 receives the content data transmitted from thecontent transmitter 1 according to the RTP (block D4), and analyzes thePMT (block D5). When a registration_descriptor is included in the PMT(YES in block D6), the content receiver 2 sets the CP flag (block D7)and, on the other hand, when a registration_descriptor is not includedin the PMT (NO in block D6), the content receiver 2 clears the CP flag(block D8). The content receiver 2 subjects the MPEG2-TS packet tofiltering by using stream information obtained by analyzing the PMT tothereby DEMUX (separate) the video ES, and audio ES from the contentdata (block D9). While the content item is transmitted from the contenttransmitter 1, the content receiver 2 repeats the above-mentionedoperations in sequence.

FIG. 6 is an exemplary flowchart showing procedures of video decodingprocessing.

When the video ES is input by the above DEMUX operation (block E1), thecontent receiver 2 analyzes the PES header (block E2). When the CP flagis set, and a PES_private_data is included therein (YES in block E3),the content receiver 2 acquires the PES_private_data (block E4), andcombines the inputCtr,StreamCtr extracted from the PES_private_data, adecryption key for the video ES generated by the key exchangeprocessing, and part (r_(iv)) of the initial vector with each other toset the decryption key and initial vector (block E5). Further, thecontent receiver 2 decrypts the encrypted PES payload according to theAES-CTR system employed in the HDCP 2.0 (block E6).

Subsequently, the content receiver 2 decodes the content data of the PESformat (block E7), and outputs the video to the display or the like(block E8). While the content item is transmitted from the contenttransmitter 1, the content receiver 2 repeats the above-mentionedoperations in sequence.

FIG. 7 is an exemplary flowchart showing procedures of audio decodingprocessing.

When the audio ES is input by the DEMUX operation (block F1), if the CPflag is set (YES in block F2), the content receiver 2 sets “copy never”as copy control information of the SCMS (block F3) and, on the otherhand, if the CP flag is clear (NO in block F2), the content receiver 2sets “copy free” as copy control information of the SCMS (block F4).That is, in the copyright-protected content transmission system of thisembodiment, the registration_descriptor (configured to notify whether ornot to require copyright protection of the video) specified by the HDCP2.0 which is the first copyright protection system to be applied tocopyright protection of the video is utilized also as informationconfigured to notify whether or not to require copyright protection ofthe audio to which the SCMS that is the second copyright protectionsystem is applied.

Subsequently, the content receiver 2 decodes the content data of the PESformat (block F5), and outputs the decoded content data to the audioreproducer 3 together with the set copy control information (block F6).While the content item is transmitted from the content transmitter 1,the content receiver 2 repeats the above-mentioned operations insequence.

The audio reproducer 3 outputs the audio data received from the contentreceiver 2 to the speaker or the like, and further carries out copycontrol of the audio in accordance with the copy control informationreceived from the content receiver 2.

As described above, the copyright-protected content transmission systemof this embodiment applies a plurality of copyright protection systemsto one content item. As has been exemplified in the above description,when the HDCP 2.0 is applied to copyright protection of the video, andthe SCMS is applied to copyright protection of the audio, it is possibleon the content transmitter 1 side to make a module (12 b) configured toencrypt/decrypt the audio unnecessary as shown in FIG. 8 under thecondition that encryption of the video is required. Likewise, on thecontent receiver 2 side too, it is possible to make a module configuredto encrypt/decrypt the audio unnecessary. That is, thecopyright-protected content transmission system of this embodimentrealizes the transmission function of the content item provided withcopyright protection at a low cost.

It should be noted that in the above description, although an example inwhich presence/absence of the registration_descriptor specified by theHDCP 2.0 (to be applied to the video) is utilized as copy control of theaudio (applying the SCMS) has been shown, copy control information maybe notified from the content transmitter 1 to the content receiver 2 bycommunication based on the real time streaming protocol (RTSP) or thelike either when the CP flag is cleared immediately after the contenttransmission application is started on the content transmitter 1 side orwhen the CP flag is set. The content receiver 2 switches copy controlinformation to be output to the audio reproducer 3 in accordance withthe received copy control information.

Further, here, although the copy control information is treated as onlyone of “copy never” and “copy free”, a case where “copy once” is handledis conceivable depending on the content item to be reproduced on thecontent transmitter 1 side.

Second Embodiment

Next, a second embodiment will be described below.

FIG. 9 is an exemplary view showing a system configuration of acopyright-protected content transmission system according to thisembodiment.

The second embodiment differs from the first embodiment in that thevideo and audio are transmitted from a content transmitter 1 todifferent transmission destination devices separate from each other. Asshown in FIG. 9, in the copyright-protected content transmission systemof this embodiment, the content transmitter 1 transmits the video to afirst content receiver 2 a, and transmits the audio to a second contentreceiver 2 b. The first content receiver 2 a is, like the firstembodiment, for example, a TV receiver, and the second content receiver2 b is, for example, an AV amplifier.

Operations of the content transmitter 1 of this embodiment are basicallyidentical to the operations of the content transmitter 1 of the firstembodiment. However, the operations of the content transmitter 1 of thisembodiment differ from those of the first embodiment in the followingpoints.

(a) that connection is established respectively between itself and thefirst content receiver 2 a, and between itself and the second contentreceiver 2 b

(b) that authentication/key-exchange processing of the HDCP 2.0 isunnecessary between itself and the second content receiver 2 b

(c) that each content data item to be transmitted to the first contentreceiver 2 a, and each content data item to be transmitted to the secondcontent receiver 2 b is generated in the MPEG2-TS format, only the videoES is included, as the ES, in the content data to be transmitted to thefirst content receiver 2 a, and only the audio ES is included, as theES, in the content data to be transmitted to the second content receiver2 b

Further, operations of each of the first content receiver 2 a, andsecond content receiver 2 b of this embodiment are basically identicalto the operations of the content receiver 2 of the first embodiment.However, the operations of the first content receiver 2 a, and secondcontent receiver 2 b of this embodiment differ from those of the contentreceiver 2 of the first embodiment in that the first content receiver 2a outputs only the video, and the second content receiver 2 b outputsonly the audio.

In the copyright-protected content transmission system of thisembodiment in which the transmission destination of the video and audiotransmitted from the content transmitter 1 is separated into the firstcontent receiver 2 a and second content receiver 2 b, too, it ispossible, on the content transmitter 1 side, to make a module (12 b)configured to encrypt/decrypt the audio unnecessary as shown in FIG. 10by applying a plurality of copyright protection systems to one contentitem. It is possible to generate content data including only the videoES as the ES, and content data including only the audio ES as the ES byproviding, for example, a switch 14 configured to selectively supply oneof the video and audio to a multiplexer module (MUX) 13. The switch 14may also be configured in such a manner that the switch 14 can bederive-controlled to supply both the video and audio to the multiplexermodule (MUX) 13.

Further, it is also possible, on the first content receiver 2 a side, tomake a module configured to encrypt/decrypt the audio unnecessary.Furthermore, it is possible; on the second content receiver 2 b side, toeliminate the existence itself of the module for encryption/decryption.That is, the copyright-protected content transmission system of thisembodiment also realizes the transmission function of the content itemprovided with copyright protection at a low cost.

Notification of copy control information about the audio from thecontent transmitter 1 to the second content receiver 2 b may be carriedout by including the registration_descriptor in the PMT of the contentdata to be transmitted from the content transmitter 1 to the secondcontent receiver 2 b or may be carried out by communication based on theRTSP or the like.

In the case where the registration_descriptor is included in the PMT,the second content receiver 2 b sets the CP flag when theregistration_descriptor is included in the PMT, and clears the CP flagwhen the registration_descriptor is not included in the PMT. When theaudio ES is input by the DEMUX operation, the second content receiver 2b sets “copy never” as copy control information of the SCMS if the CPflag is set, and sets “copy free” as copy control information of theSCMS if the CP flag is clear.

On the other hand, in the case of communication based on the RTSP or thelike, the second content receiver 2 b switches the copy control inaccordance with copy control information received from the contenttransmitter 1.

It should be noted that here an example in which the content transmitter1 transmits content data including only the video ES as the ES to thefirst content receiver 2 a, and transmits content data including onlythe audio ES as the ES to the second content receiver 2 b has beenshown. However, the example is not limited to this, and the same contentdata including both the video ES and the audio ES as the ES may betransmitted to both the first content receiver 2 a and second contentreceiver 2 b in a multicasting manner. That is, each of the firstcontent receiver 2 a, and second content receiver 2 b may eclecticallyselect ESs. In any event, the content transmitter 1 transmits the videoES and audio ES from one communication module such as a Wi-Fi module orthe like to the outside.

The various modules of the systems described herein can be implementedas software applications, hardware and/or software modules, orcomponents on one or more computers, such as servers. While the variousmodules are illustrated separately, they may share some or all of thesame underlying logic or code.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. An electronic device configured to transmit a content item comprising video data and audio data, the device comprising: a video encoder configured to encode video data to generate a video packetized elementary stream (PES); an encryptor configured to encrypt the video PES encoded by the video encoder, by using an encryption system complying with an HDCP standard; an audio encoder configured to encode audio data to generate an audio PES; a multiplexer configured to generate multiplexed data complying with an MPEG-2 TS format, the multiplexed data comprising the video PES encrypted by the encryptor and the audio PES not subjected to encryption complying with the HDCP standard, the multiplexer being configured to insert a registration descriptor specified by the HDCP standard in a program map table (PMT) in the multiplexed data when copyright protection is required for the video PES and the audio PES, the registration descriptor indicating that the video PES is encrypted by using an encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and a content transmitter configured to output, by using an RTP protocol, the multiplexed data generated by the multiplexer to an external device via a wireless transmission path, wherein: the external device prohibits copying of both the video PES encrypted in accordance with the HDCP standard and the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is inserted in the PMT in the multiplexed data, the registration descriptor indicating that the video PES is encrypted by using the encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and the external device permits copying of the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is not inserted in the PMT in the multiplexed data.
 2. An electronic device configured to receive a content item comprising video data and audio data, the device comprising: a content receiver configured to receive, by using an RTP protocol, multiplexed data complying with an MPEG-2 TS format from a wireless transmission path, the multiplexed data comprising a video PES encrypted by using an encryption system complying with an HDCP standard and an audio PES not subjected to encryption complying with the HDCP standard; and a processor configured to: prohibit copying of the audio PES not subjected to encryption complying with the HDCP standard in the multiplexed data if a registration descriptor specified by the HDCP standard is inserted in a program map table (PMT) in the multiplexed data, the registration descriptor indicating that the video PES is encrypted by using the encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and permit copying of the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is not inserted in the PMT in the multiplexed data.
 3. A method of transmitting a content item for an electronic device which transmits the content item comprising video data and audio data, the method comprising: encoding video data to generate a video PES; encrypting the video PES, by using an encryption system complying with an HDCP standard; encoding audio data to generate an audio PES; generating multiplexed data complying with an MPEG-2 TS format, the multiplexed data comprising the encrypted video PES and the audio PES not subjected to encryption complying with the HDCP standard, the generating comprising inserting a registration descriptor specified by the HDCP standard in a program map table (PMT) in the multiplexed data when copyright protection is required for the video PES and the audio PES, the registration descriptor indicating that the video PES is encrypted by using an encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and outputting, by using an RTP protocol, the multiplexed data to an external device via a wireless transmission path, wherein: the external device prohibits copying of both the video PES encrypted in accordance with the HDCP standard and the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is inserted in the PMT in the multiplexed data, the registration descriptor indicating that the video PES is encrypted by using the encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and the external device permits copying of the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is not inserted in the PMT in the multiplexed data.
 4. A method of receiving, by an electronic device, a content item comprising video data and audio data, the method comprising: receiving by a content receiver, by using an RTP protocol, multiplexed data complying with an MPEG-2 TS format from a wireless transmission path, the multiplexed data comprising a video PES encrypted by using an encryption system complying with an HDCP standard and an audio PES not subjected to encryption complying with the HDCP standard; prohibiting, by a processor, copying of the audio PES not subjected to encryption complying with the HDCP standard in the multiplexed data when a registration descriptor specified by the HDCP standard is inserted in a program map table (PMT) in the multiplexed data, the registration descriptor indicating that the video PES is encrypted by using the encryption system complying with the HDCP standard and not indicating that the audio PES is to be protected in accordance with the HDCP standard; and permitting copying of the audio PES not subjected to encryption complying with the HDCP standard if the registration descriptor is not inserted in the PMT in the multiplexed data. 